1. Field of the Invention
The present invention relates to a tailgate of an automotive vehicle, and more particularly to a tailgate structure for automotive vehicle and manufacturing method thereof adapted to change a tailgate structure for reduction of manufacturing cost and for shortened manufacturing process.
2. Description of the Prior Art
Generally, a tailgate 10 mounted at a rear end of a passenger car, openable/closeable for accommodation of various freights, is hinged at an upper end thereof to a rear tip end of a roof panel 2 of a body 1 of an automotive vehicle (hereinafter referred to as vehicle body), such that the tailgate 10 is vertically rotated, and opened and closed.
Furthermore, the tailgate 10 includes, as illustrated in FIG. 2, an inner panel 12 centrally cut in rectangular shape and formed with an opening 13, an outer panel 14 centrally formed with an opening 15 to be coupled to the inner panel 12 and a door glass 16 fixedly installed on the openings 13 and 15 of the inner panel 12 and the outer panel 14.
At this locations, the inner panel 12 is coupled at left and right sides thereof with reinforcing panels 18 respectively, where each reinforcing panel 18 is outwardly bent from a hinge point 12a provided for hinge with the roof panel 2 of vehicle body 1 while each hinge point is located on an upper left and right side of the inner panel 12. The reinforcing panel 18 is also extended to a lower corner area 12b of the opening 13 at the inner panel 12 to again be inwardly bent. The reinforcing panel 18 serves to reinforce a structural strength at a part weak to bending force and torsional strength received by the tailgate 10 when the tailgate 10 is opened and closed.
Meanwhile, manufacturing process of the tailgate 10 comprising the inner panel 12, outer panel 14, door glass 16 and the reinforcing panel 18 will be described.
The tailgate 10 is manufactured by the following processes, the processes comprising the steps of: separately manufacturing the inner panel 12, outer panel 14 and reinforcing panel 18 through respective pressing processes; spot-welding and joining the reinforcing panel 18 from upper left/right hinge points 12a of the inner panel 12 to the lower corner area 12b; hemming a marginal area of the outer panel 14 about a marginal area of the inner panel 12 to thereby join with sealant; and assembling the door glass 16 through the openings 13 and 15 of the inner panel 12 and outer panel 14 via a glass molding material (not shown).
However, there is a problem in the tailgate 10 thus manufactured through the above-mentioned processes in that the opening 13 is formed through a steel panel cut in approximate rectangular shape in the forming of the inner panel 12 out of the press-utilized forming processes to thereby result in an unnecessary waste as much as the cut portion (generally called as scrap).
There is another problem in that the tailgate 10 is lengthily extended from a hinge point 12a of the inner panel 12 to the lower corner area 12b of the opening 13, such that the reinforcing panel 18 is additionally joined for structural strength reinforcement of the tailgate 10, thereby increasing the manufacturing cost due to additional consumption of raw material and assembly processes.
There is still another problem in that the reinforcing panel 18 joined from the upper left/right points 12a to the lower corner are 12b of the inner panel 12 is spot-welded for coupling, such that a general spot welding generates a concentration of stress to a junction part and brings forth a weakness of welding strength around the junction part, thereby deteriorating durability of the tailgate 10.